Multitube catalytic reactors may comprise several tens of thousands of tubes, which constitute as many reaction compartments. Because the catalyst becomes deactivated over time, it is necessary periodically to replace the catalyst, i.e. to empty the tubes and fill the tubes with fresh catalyst.
This is a complex operation which may take several weeks to complete properly, representing a significant cost to the operator. It is therefore desirable for the method of filling the reactor to be as rapid as possible.
One of the main constraints on the operation is the need to meter precisely the quantity of catalyst (generally in granular form) in each reaction tube. Any heterogeneity between the filling of the various tubes in fact leads to a difference in pressure drop between reactor compartments, hence reducing efficiency. It also makes it possible to avoid any preferred passage of reaction gas or any bypassing of catalyst in the tube.
Document EP 0 963 785 describes a filling device for introducing granular catalyst into reaction tubes. The device is fixed to the inlet of the tubes and channels a stream of catalysts introduced into the tubes.
Document EP 1 654 054 describes filling sleeves that allow controls on the height of the catalyst inside the reaction tubes.
However, catalytic reactors often contain two or even three layers of different catalysts. These layers need to be placed in the reaction tubes in a precise order and with well-defined layer thicknesses. Now, the prior art does not allow satisfactory management of the filling of a multitube reactor with several catalysts, notably when, in order to speed up the filling process, it is desirable to fill the various catalysts simultaneously on a reactor scale.
There is therefore a need to develop a method for filling a reactor with a plurality of catalysts that is more effective and/or more rapid than in the prior art.